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This work demonstrates experimentally the use of mass spectrometry (MS) for on-line, quantitative monitoring of organophilic pervaporation processes operated not only under variable conditions of tem- perature of condensation/downstream pressure but also when using complex multi-component feed streams. Due to its high sensitivity, mass spectrometry is particularly suitable for on-line monitoring of aromas in dilute streams under reduced pressure, as happens with natural aromas in permeate streams. Mass spectrometry is also suitable for on-line monitoring of solvent and co-solvent permeants (water and ethanol in the selected case study), enabling for on-line determination of selectivity of the solutes of interest. A new method of calibration is proposed and validated, which correlates the intensity of the characteristic mass peak mi/z for each compound of interest with its partial pressure in the perme- ate stream. Moreover, mass spectrometry proves to be a powerful tool for studying the fractionation of aromas, recovered by integrated pervaporation–condensation processes, allowing on-line monitoring of each solute vapour in the permeate stream. Additionally, this technique enables for accurate transient studies due to the possibility of acquiring one data point every 12–15s (potentially less, if desired) in real-time.
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